Our goal is to develop VTC-MS3 as a novel tolerance-inducing therapeutic to treat Multiple Sclerosis (MS). MS is the most common demyelinating disorder of the Central Nervous System (CNS), affecting approximately 2.3 million people worldwide and 400,000 in the US alone28, 29. Current and developing treatment of MS relies mainly on immuno-suppression and modulation to reduce inflammatory symptoms14, 15, 26, 30, 31 creating a significant need for new therapeutics that treat the underlying cause. For successful induction of immune tolerance, mucosal tissues play a significant role32-34. The epithelial layers that cover the Gut Associated Lymphoid Tissue (GALT) and Nasopharyngeal Associated Lymphoid Tissue (NALT) areas contain a subpopulation of specialized cells (microfold or M cells) which sample environmental antigens and present them to the adjacent immune cells35, 36. A number of studies now confirm that these cells play a crucial role in the generation of tolerance to a given antigen37-40. Reoviruses are segmented, doublestranded RNA viruses that bind and infect humans via mucosal surfaces using the viral coat protein, p?141, 42. We have demonstrated that fusion proteins consisting of p?1 fused to an antigen of choice can bind to M cells and generate a tolerigenic immune response to that antigen37-40, 43. The ability of p?1-antigen targeting to induce tolerance has been studied in both allergy and autoimmune models, including the mouse EAE model of MS, using both oral and intranasal dosing routes37, 38, 43, 44. These studies demonstrate that p?1-mediated tolerance to the MS auto-antigen, MOG, but not recombinant MOG alone, entirely prevents CNS pathology and clinical manifestation of EAE. The tolerance response is antigen specific, and due to the induction of antiinflammatory cytokines and an increase in suppressive regulatory T cells (Tregs)37, 38, 43, 44 The goal of this Fast-track SBIR application is to develop VTC-MS3 as an orally administered, tolerance therapeutic for the treatment of MS. VTC-MS3 is a recombinant protein consisting of p?1 fused to three of the major MS autoantigens; myelin oligodendrocyte glycoprotein (MOG), myelin basic protein (MPB), and antigenic regions of proteolipid protein (PLP). This design allows VTC-MS3 to exploit p?1 targeting of MS auto-antigens specifically to M cells, and to induce tolerance to a broad array of antigenic epitopes within these antigens. The key objectives are to: 1) establish VTC-MS3 production and analytical assays to support manufacturing, purification, bioactivity determination, and formulation; 2) define the IND-enabling studies to support our clinical study design, and 3) develop non-GLP and GLP preclinical datasets to help us obtain FDA IND approval. Successful commercialization of VTC-MS3 would ultimately provide a profound front-line medical advancement in the treatment of MS.